The present invention relates in general to dispensers, and, more particularly, to dry product dispensers.
There are many proposals for dispensing product, such as dry powder, or the like. Among these proposals are the devices disclosed in U.S. Pat. Nos.: 456,205; 2,358,329; 3,162,332; 2,598,291; 3,625,403; and 3,704,811.
However, all of these devices suffer several disadvantages. None of these devices properly fluidize the dry product during operation, and hence suffer drawbacks related to product clumping, or the like. Clogging and/or "mudding" may occur during the operation of these devices.
In particular, U.S. Pat. No. 3,598,291 uses the principle of channeling the propellant gas through a second container of powder, whereby fluidization picks up the powder. The powder/gas mixture then exits the powder container through a directive nozzle. This design proves to be inadequate in practice for several reasons:
1. No method is given for preventing powder from entering the discharge tube when the container is not in use. Ordinary shipping and handling will cause this tube to fill with powder. When a discharge valve is opened, gas pressure builds in the powder container until the discharge tube clears, or the container bursts. It is noted that all forms of this invention require two containers capable of withstanding full pressure which is expensive. It would not be possible to store the powder in a plastive overcap. The embodiment disclosed in FIG. 6 of this patent does not lend itself to suitable methods of closure for funnell 44 and/or ejection nozzle 48.
2. In the operation of the FIG. 6 embodiment, the gas is brought through the powder in the fluidization process. However, if the can is moved during operation, small amounts of liquid propellant will move into the powder container before vaporizing. Formations of "mud" result, causing clogging of the discharge tube, and hardened, caked powder between the gas outlet and the discharge path, thus preventing future mixing of the gas and powder.
3. The process of fluidization requires a large amount of gas flowing though the powder. The rapid boiling of the liquid propellant to provide this gas chills the propellant, dropping propellant pressure and reducing gas flow. This aggravates the aforementioned problem of "mudding". The continuous flow of gas results in heavy concentration of powder, thereby negating the device for consumer applications.
The assembly disclosed device overcomes these drawbacks and provides an easily and efficiently manufactured dry powder dispensing device.